The present invention relates to a lightweight part, particularly a vehicle body part, which includes sheet steel and light metal.
A cast vehicle construction part made of a light metal alloy having a sheet steel structure that is cast on or cast in is known from German Unexamined Application DE 41 03 036 A1. The sheet steel structure either forms the vehicle outer skin or a flange for connection to a further vehicle part. In the known vehicle construction part, the sheet steel structure is connected to the light metal alloy over its entire surface. It is possible to provide targeted cavities in the vehicle construction part. DE 41 03 036 A1 teaches reinforcing such cavities through the cast-in sheet steel structure. Casting in the sheet steel structure has been shown to be difficult in practice.
A lightweight part made of a shell-shaped main body, whose inner space has reinforcement ribs, is known from European Patent Specification EP 0 370 342 B1. The reinforcement ribs are made of molded-in plastic and are connected to the main body at discrete connection points via openings. The plastic extends through the openings into the main body and beyond the areas of the openings. Structural limits are placed on the performance of the plastic (especially taking the temperature dependence into consideration) through the selection of the material combination. In the event of extreme loads, plastic tends to crumble.